Defects in sexual development in the human embryo are alarmingly common and profoundly distressing. The basis of these disorders is often a failure in the delicate network of gene regulation that controls proper development of the gonads. In mammals, the initial trigger of the cascade of gene regulation responsible for testis differentiation is the transcription factor SRY. Although a number of genes are assumed to act downstream of Sry in this cascade, no direct SRY target gene has yet been identified. This project will use a unique antibody that recognizes endogenous mouse SRY protein, recently generated in our laboratory. This antibody will be used in chromatin immunoprecipitation experiments to identify genes that are under direct control of SRY. This information will be critical in building a comprehensive picture of male sex determination and explaining the etiology of human sexual development anomalies. [unreadable] [unreadable]